It has been known for some time that drugs and medical instruments and implements have to be irradiated so that they will not cause patients to become ill from harmful bacteria when they are applied to the patients. Systems have accordingly been provided for irradiating drugs and medical instruments and implements. The drugs and the medical instruments and implements have then been stored in sterilized packages until they have been ready to be used.
In recent years, it has been discovered that foods can carry harmful bacteria if they are not processed properly or, even if they are processed properly, that the foods can harbor and foster the proliferation of such harmful bacteria if they are not stored properly or retained under proper environmental conditions such as temperature. Some of the harmful bacteria can even be deadly.
For example, harmful bacteria have been discovered in recent years in hamburgers prepared by one of the large hamburger chains. Such harmful bacteria have caused a number of purchasers of hamburgers at stores in the chain to become sick. As a result of this incident and several other similar incidents, it is now recommended that hamburgers should be cooked to a well done, or at least a medium, state rather than a medium rare or rare state. Similarly, harmful bacteria have been found to exist in many chickens that are sold to the public. As a result of a number of incidents which have recently occurred, it is now recommended that all chickens should be cooked until no blood is visible in the cooked chickens.
To prevent incidents such as discussed in the previous paragraphs from occurring, various industries have now started to irradiate foods before the foods are sold to the public. This is true, for example, of hamburgers and chickens. It is also true of fruits, particularly fruits which are imported into the United States from foreign countries.
In previous years, gamma rays have generally been the preferred medium for irradiating various articles. The gamma rays have been obtained from a suitable material such as cobalt and have been directed to the articles to be irradiated. The use of gamma rays has had certain disadvantages. One disadvantage is that irradiation by gamma rays is slow. Another disadvantage is that irradiation by gamma rays is not precise. This results in part from the fact that the strength of the source (e.g. cobalt) of the gamma rays decreases over a period of time. It also results in part from the fact that the gamma rays cannot be directed in a sharp beam to the articles to be irradiated. This prevents all of the gamma rays from being useful in irradiating the articles.
In recent years, electron beams have been directed to articles to irradiate the articles. Electron beams have certain advantages over the use of gamma rays to irradiate articles. One advantage is that irradiation by electron beams is fast. For example, a hamburger patty having a square cross section can be instantaneously irradiated by a passage of an electron beam of a particular intensity through the hamburger patty. Another advantage is that irradiation by an electron beam is relatively precise because the strength of the electron beam remains substantially constant even when the electron beam continues to be generated over a long period of time.
X-rays have also been used to irradiate articles. The x-rays may be formed from electron beams. An advantage in irradiating articles with x-rays is that the articles can be relatively thick. For example, x-rays can irradiate articles which are thicker than the articles which are irradiated by electron beams. A disadvantage is that the x-rays cannot be focused in a sharply defined beam.
The systems now in use are relatively complicated and relatively expensive and occupy a considerable amount of space. These systems are particularly effective when used at companies requiring radiation of large volumes of products at a particular location. These companies are generally large and have considerable assets. No system apparently exists for irradiating reduced volumes of products at a particular location. No system also apparently exists for use by companies of small or medium size.
Co-pending application Ser. No. 09/971,986, filed on Oct. 4, 2001 by Gary K. Loda for a Compact Self-Shielded Irradiation System and Method and assigned of record to the assignee of record of this application discloses and claims a system for, and method of, providing a simplified system operative in a minimal space, and having a minimal cost, for irradiating products without any significant sacrifice in the quality of the radiation of the products compared to the irradiation provided in the prior art. The invention disclosed and claimed in co-pending application Ser. No. 09/971,986 is particularly effective for use by companies of small or medium size or where the irradiation of products is only sporadic.
An accelerator in the system disclosed and claimed in co-pending application Ser. No. 09/971,986 provides radiant energy in a first direction. A carousel and first and second members have a common axis in the first direction. The carousel, preferably having a hollow cylindrical configuration, has a ring-shaped configuration defined by inner and outer diameters. The first member has an outer diameter preferably contiguous to the inner diameter of the carousel.
The second member has an inner diameter preferably contiguous to the outer diameter of the carousel. The first and second members provide shielding against the radiant energy from the accelerator.
A single motor (e.g., a stepping member) rotates the carousel past the radiant energy in co-pending application Ser. No. 09/971,986 continuously at a substantially constant speed in successive revolutions. Vanes made from a shielding material are disposed at spaced positions in the carousel to divide the carousel into compartments for receiving the articles and to isolate each compartment against the radiant energy in other compartments.
A loader in co-pending application Ser. No. 09/971,986 loads the articles into compartments before the movement of the articles in the compartments past the radiant energy. An unloader in co-pending application Ser. No. 09/971,986 unloads the articles from the compartments after the movement of the articles in the compartments past the radiant energy.
Another system exists in the prior art for irradiating articles. The system includes a conveyor movable in a first direction past an article which receives radiation in a second direction substantially perpendicular to the first direction. The article has variable characteristics in a third direction substantially perpendicular to the first and second directions. A system has been disclosed in co-pending application Ser. No. 09/912,576 filed on Jul. 24, 2001 by John Thomas Allen, George M. Sullivan and Colin Brian Williams for Fixtures For Providing An Irradiation Within Acceptable Limits and assigned of record to the assignee of record of this application. Co-pending application Ser. No. 09/912,576 discloses a non-electronic system for, and method of, compensating for differences in the characteristics of the article in the third direction to obtain a substantially constant irradiation at the different positions in the article regardless of the differences in the characteristics of the article in the third direction.